Dissolve the yeast in water, add sugar, salt and butter, gradually mix in the flour. Put in the fridge for 60 minutes. The risen dough is formed into two loaves and cover with a towel for 15 minutes. Repeat the steps and put the dough in. Give to rise in a warm place for 60 minutes. Gently put the dough on a baking sheet and put in hot oven (160-180*C) 75-80 minutes.